For the cake:
1 stick (8 tablespoons) butter, at room temperature
3/4 cup sugar
1 teaspoon vanilla
1 cup cake flour
1/3 cup Dutch-processed cocoa powder
1/2 teaspoon baking powder
1/4 teaspoon baking soda
1/2 cup milk, 2% or higher
For the pudding:
1/2 cup milk
1/2 cup packed light brown sugar
1/4 cup smooth peanut butter
2 tablespoons cornstarch
1 egg yolk
1 tablespoon butter
1 tablespoon bourbon (optional)
1/2 teaspoon vanilla
For the topping:
1 cup heavy whipping cream
2 tablespoons powdered sugar
1/2 teaspoon vanilla
1 tablespoon grated chocolate, for garnish
Heat the oven to 350 F and spray an 8×8-inch cake pan with non-stick cooking spray. Line the pan with parchment paper, making sure there is a two inch overhang on either side of the pan, and spray the parchment with non-stick cooking spray.
In a large bowl cream together the butter and sugar until well combined and somewhat lighter in color. Add the egg and vanilla and mix until uniformly mixed.
In a medium bowl sift together the flour, cocoa powder, baking powder, and baking soda.
Alternately add the flour mixture and milk into the butter in three additions, beginning and ending with the flour.
Pour the mixture into the prepared pan and spread so the patter is even. Bake for 25 to 30 minutes, or until the cake springs back when gently pressed in the center, and the edges of the cake pull away from the sides of the pan. Do not over-bake.
During the last 12 minutes of baking prepare the pudding.
In a blender combine the milk, brown sugar, peanut butter, cornstarch, and egg yolk. Blend until smooth, about 30 seconds, then transfer the mixture into a saucepan. Cook over medium heat, whisking constantly, until the mixture comes to a boil. Cook for 1 minute then remove from the heat. Add the butter, bourbon, and vanilla.
Once the cake comes out of the oven immediately poke holes into the cake with the end of a large wooden spoon. Pour the hot pudding over the cake, tapping the cake gently on the counter to release any air bubbles and make sure the pudding is in the holes. Cover the cake with plastic and cool on the counter for 1 hour, then chill for at least 4 hours or overnight.
Just before serving prepare the topping. In a stand mixer, or a large bowl with a hand mixer, combine the cream, powdered sugar, and vanilla. Whip until the mixture forms soft peaks, about 2 minutes. Spread the whipped cream over the cake and garnish with grated chocolate.
Found here http://www.rfgkitchenrelax.blogspot.com/2013/10/chocolate-peanut-butter-pudding-poke.html